The organism commonly known as the lawn shrimp is actually a terrestrial amphipod, a type of crustacean more closely related to marine life than to insects. These creatures, sometimes called scuds or land hoppers, become a nuisance when their populations swell and they migrate from the yard. These migrations often end with large numbers of the small animals dying on paved surfaces or inside homes. This guide provides steps to eliminate the current population and modify the environment to prevent their permanent return.
Identifying the Amphipod and Understanding Their Presence
Lawn shrimp are small, ranging from 3.5 to 20 millimeters in length, and have a distinctive laterally compressed, or side-to-side flattened, body shape. When alive, they are typically pale brown, greenish, or brownish-black, but they turn pink or red when they die from desiccation. They are often mistaken for springtails because of their ability to jump when disturbed.
These amphipods are scavengers that break down organic matter, meaning they do not damage living plants or turf. Their presence indicates two required environmental conditions: high moisture and abundant decaying organic debris. They lack a waxy coating on their exoskeleton, making them highly susceptible to water loss. They must remain in perpetually damp areas, such as moist soil, under leaf litter, or within thick layers of mulch.
The high-moisture requirement explains why they migrate in large numbers after heavy rainfall or excessive irrigation. Waterlogged soil forces them to leave their habitat, driving them onto sidewalks, patios, or into structures where they ultimately dry out and perish. Managing moisture and organic debris is the core strategy for long-term control.
Immediate Strategies for Population Reduction
For immediate relief from migrating lawn shrimp, physical removal is the most direct and effective method. Piles of dead or dying amphipods can be safely removed from paved areas or entry points by sweeping them up with a broom and dustpan. A vacuum cleaner is also effective for quickly collecting the small crustaceans from dry surfaces, especially those that have already died inside the home.
A temporary reduction in the moisture level of the immediate area will accelerate the decline of the existing population. Stopping the watering schedule for several days will force the ground cover and mulch to dry out. This temporary desiccation is often enough to eliminate a large number of the moisture-dependent creatures.
Chemical treatments are generally considered ineffective because their population density is tied to environmental conditions, and no specific insecticidal products are labeled for their control. If large numbers are clustered on a foundation or patio, a light application of diatomaceous earth (DE) can be used. Diatomaceous earth is a finely powdered substance that causes physical damage to the amphipods’ exterior, leading to rapid desiccation and death on contact.
Permanent Environmental Modifications
Achieving permanent removal requires cultural practices that make the environment inhospitable to the amphipods. The primary modification is achieving better moisture control throughout the landscape. This includes adjusting automatic irrigation systems to water less frequently but more deeply, allowing the top layer of soil and mulch to dry out between cycles.
Another element is identifying and repairing water leaks from outdoor faucets, condensation lines, or downspouts that create continuously saturated spots near the home. Improving drainage in water-prone areas, perhaps by aerating the lawn or installing a French drain, will prevent standing water that drives them indoors.
Managing the food source is the second long-term modification, specifically by reducing decaying organic matter. This involves promptly removing grass clippings, fallen leaves, and other plant debris from garden beds and the base of the foundation. Excessive layers of mulch should be reduced to a depth of no more than two to three inches to allow for better air circulation and drying near the soil surface.
Finally, ensuring the home’s perimeter is sealed will prevent any remaining stragglers from entering the structure. This involves installing or replacing weather stripping on exterior doors to eliminate gaps. Also, sealing any cracks, crevices, or utility penetrations in the foundation will physically block the pathways these small creatures use to enter the home.